Document Detail

Pressure Overload Differentially Affects Respiratory Capacity in Interfibrillar and Subsarcolemmal Mitochondria.
MedLine Citation:
PMID:  23241325     Owner:  NLM     Status:  Publisher    
Years ago a debate arose whether two functionally different mitochondrial subpopulations (subsarcolemmal - SSM and interfibrillar - IFM) exist in heart muscle. Nowadays potential differences are often ignored. Presumably, SSM are providing ATP for basic cell function while IFM provide energy for the contractile apparatus. We speculated that two distinguish-able subpopulations exist that are differentially affected by pressure overload. Male Sprague-Dawley rats were subjected to transverse aortic constriction (TAC) for 20 weeks or sham operation. Contractile function was assessed by echocardiography. Heart tissue was analyzed by electron-microscopy. Mitochondria were isolated by differential centrifugation and respiratory capacity was analyzed using a Clark electrode. Pressure overload (PO) induced left ventricular hypertrophy with increased posterior wall diameter and impaired contractile function. Mitochondrial state 3 respiration in control was 50% higher in IFM than in SSM. PO significantly impaired respiratory rates in both IFM and in SSM, but in SSM to a lower extent. As a result, there were no differences between SSM and IFM after 20 weeks of pressure overload. PO reduced total citrate synthase activity, suggesting reduced total mitochondrial content. Electron microscopy revealed normal morphology of mitochondria but reduced total mitochondrial volume density. Conclusion: Differences in respiratory capacity of interfibrillar and subsarcolemmal mitochondria exist and IFM show greater respiratory capacity depression by pressure overload than SSM. The strong effect of pressure overload on IFM together with the simultaneous appearance of mitochondrial and contractile dysfunction seems to support the notion of IFM primarily producing ATP for contractile function.
Michael Schwarzer; Andrea Schrepper; Paulo A Amorim; Torsten Doenst
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-12-15
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  -     ISSN:  1522-1539     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-17     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1University Hospital of Jena - Friedrich-Schiller-University of Jena.
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